This invention relates generally to a rejector drive system for sorting apparatus and more particularly to a system in which the acceleration-velocity characteristics of the rejector are controlled.
In agriculture, harvesters are employed to harvest the produce from the plants or vines and direct the produce into conveyor belts to present the produce to an inspection station where (damaged, spoiled, overripe, or underripe produce) are rejected. Recent developments have provided photoelectric scanning systems which scan the produce and generate reject signals for rejecting the culls. The reject signals are then employed to control a reject apparatus.
One type of such reject apparatus employs a bopper which hits the produce to be rejected and deflects the produce from the belt into a reject bin or onto the ground. The action of the bopper must be rapid to reject a cull and return to a ready position to strike the next following produce if it is also to be rejected. Generally the bopper is driven by an air cylinder to which air pressure is selectively applied responsive to the reject signal. Full pressure is applied to the air cylinder throughout the stroke so that it rapidly accelerates to bop or strike the produce and thereafter the air is applied to rapidly return the piston to its ready position. The piston is physically stopped at its extreme positions. This gives rise to high impact forces. The impact forces at the two extreme positions of the piston cause cracking at the pneumatic cylinders at various locations, breakage of fittings, loosening of parts, and cracking of supports.
Similar problems are encountered in sorting systems for sorting other objects or articles in which pistons are employed to reject unwanted objects or articles.
Various attempts have been made to cure the problem without success. For example, the cylinders are operated with the minimum pressure which will result in the required stroke lenght ad stroke time. This of course reduces the impact forces to a minimum which is controlled by the required stroke length and time. Other attempts to cure include the use of elastic mounts, less massive fittings, strain reliefs, control of the pressure pulse applied to the air cylinder. However, all such solutions have not been entirely satisfactory.